Exercise machine



FIG. 1 is a perspective view of an exercise machine showing our new design;

FIG. 2 is a side elevational view thereof, the opposite side being a mirror image thereof;

FIG. 3 is an end elevational view thereof;

FIG. 4 is an end elevational view thereof of the opposite end shown in FIG. 3; and

FIG. 5 is a top plan view thereof. 

The ornamental design for an exercise machine, as shown and described. 